1. Field of the Invention
This invention relates to an embroidering-frame driving device for a sewing machine, and a method of controlling the device.
2. Discussion of the Related Art
An embroidering-frame driving device has been developed for a sewing machine which moves with respect to the sewing needle an embroidering frame to which a piece of cloth has fastened tight, so that a given pattern is embroidered on the piece of cloth. An embroidering-frame driving device of this type has been disclosed, for instance, by Japanese Patent Examined Publication No. Sho 60-42740, Japanese Utility Model Examined Publication No. Sho 61-40289 and U.S. Pat. No. 5,003,895. The conventional embroidering-frame driving device has an X-axis and Y-axis which are orthogonal with each other. The embroidering frame is moved in the directions of X-axis and Y-axis so that the piece of cloth fastened to the embroidering frame is moved in a horizontal plane with respect to the sewing needle.
The conventional embroidering-frame driving device, being operated on the X- and Y-axes, is unavoidably intricate in structure, and accordingly high in manufacturing cost. In addition, the device is large in frame drive weight, which makes it impossible to increase the sewing speed (rpm). Furthermore, the sewing machine equipped with the device is bulky, requiring a large installation space.